/*
 * pgp-info.c
 *	  Provide info about PGP data.
 *
 * Copyright (c) 2005 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *	  notice, this list of conditions and the following disclaimer in the
 *	  documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.	IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * contrib/pgcrypto/pgp-info.c
 */
#include "postgres.h"
#include "knl/knl_variable.h"

#include "px.h"
#include "mbuf.h"
#include "pgp.h"

static int read_pubkey_keyid(PullFilter* pkt, uint8* keyid_buf)
{
    int res;
    PGP_PubKey* pk = NULL;

    res = _pgp_read_public_key(pkt, &pk);
    if (res < 0)
        goto err;

    /* skip secret key part, if it exists */
    res = pgp_skip_packet(pkt);
    if (res < 0)
        goto err;

    /* is it encryption key */
    switch (pk->algo) {
        case PGP_PUB_ELG_ENCRYPT:
        case PGP_PUB_RSA_ENCRYPT:
        case PGP_PUB_RSA_ENCRYPT_SIGN:
            memcpy(keyid_buf, pk->key_id, 8);
            res = 1;
            break;
        default:
            res = 0;
    }

err:
    pgp_key_free(pk);
    return res;
}

static int read_pubenc_keyid(PullFilter* pkt, uint8* keyid_buf)
{
    uint8 ver;
    int res;

    GETBYTE(pkt, ver);
    if (ver != 3)
        return -1;

    res = pullf_read_fixed(pkt, 8, keyid_buf);
    if (res < 0)
        return res;

    return pgp_skip_packet(pkt);
}

static const char hextbl[] = "0123456789ABCDEF";

static int print_key(uint8* keyid, char* dst)
{
    int i;
    unsigned c;

    for (i = 0; i < 8; i++) {
        c = keyid[i];
        *dst++ = hextbl[(c >> 4) & 0x0F];
        *dst++ = hextbl[c & 0x0F];
    }
    *dst = 0;
    return 8 * 2;
}

static const uint8 any_key[] = {0, 0, 0, 0, 0, 0, 0, 0};

/*
 * dst should have room for 17 bytes
 */
int pgp_get_keyid(MBuf* pgp_data, char* dst)
{
    int res;
    PullFilter* src = NULL;
    PullFilter* pkt = NULL;
    int len;
    uint8 tag;
    int got_pub_key = 0, got_symenc_key = 0, got_pubenc_key = 0;
    int got_data = 0;
    uint8 keyid_buf[8];
    int got_main_key = 0;

    res = pullf_create_mbuf_reader(&src, pgp_data);
    if (res < 0)
        return res;

    while (1) {
        res = pgp_parse_pkt_hdr(src, &tag, &len, 0);
        if (res <= 0)
            break;
        res = pgp_create_pkt_reader(&pkt, src, len, res, NULL);
        if (res < 0)
            break;

        switch (tag) {
            case PGP_PKT_SECRET_KEY:
            case PGP_PKT_PUBLIC_KEY:
                /* main key is for signing, so ignore it */
                if (!got_main_key) {
                    got_main_key = 1;
                    res = pgp_skip_packet(pkt);
                } else
                    res = PXE_PGP_MULTIPLE_KEYS;
                break;
            case PGP_PKT_SECRET_SUBKEY:
            case PGP_PKT_PUBLIC_SUBKEY:
                res = read_pubkey_keyid(pkt, keyid_buf);
                if (res < 0)
                    break;
                if (res > 0)
                    got_pub_key++;
                break;
            case PGP_PKT_PUBENCRYPTED_SESSKEY:
                got_pubenc_key++;
                res = read_pubenc_keyid(pkt, keyid_buf);
                break;
            case PGP_PKT_SYMENCRYPTED_DATA:
            case PGP_PKT_SYMENCRYPTED_DATA_MDC:
                /* don't skip it, just stop */
                got_data = 1;
                break;
            case PGP_PKT_SYMENCRYPTED_SESSKEY:
                got_symenc_key++;
                /* fallthru */
            case PGP_PKT_SIGNATURE:
            case PGP_PKT_MARKER:
            case PGP_PKT_TRUST:
            case PGP_PKT_USER_ID:
            case PGP_PKT_USER_ATTR:
            case PGP_PKT_PRIV_61:
                res = pgp_skip_packet(pkt);
                break;
            default:
                res = PXE_PGP_CORRUPT_DATA;
        }

        if (pkt)
            pullf_free(pkt);
        pkt = NULL;

        if (res < 0 || got_data)
            break;
    }

    pullf_free(src);
    if (pkt)
        pullf_free(pkt);

    if (res < 0)
        return res;

    /* now check sanity */
    if (got_pub_key && got_pubenc_key)
        res = PXE_PGP_CORRUPT_DATA;

    if (got_pub_key > 1)
        res = PXE_PGP_MULTIPLE_KEYS;

    if (got_pubenc_key > 1)
        res = PXE_PGP_MULTIPLE_KEYS;

    /*
     * if still ok, look what we got
     */
    if (res >= 0) {
        if (got_pubenc_key || got_pub_key) {
            if (memcmp(keyid_buf, any_key, 8) == 0) {
                memcpy(dst, "ANYKEY", 7);
                res = 6;
            } else
                res = print_key(keyid_buf, dst);
        } else if (got_symenc_key) {
            memcpy(dst, "SYMKEY", 7);
            res = 6;
        } else
            res = PXE_PGP_NO_USABLE_KEY;
    }

    return res;
}
